class ConcreteVisitor implements Visitor {

    @Override
    public void visit(ConcreteElementA element) {
        System.out.println("访问者正在运行 " + element.operationA());
    }

    @Override
    public void visit(ConcreteElementB element) {
        System.out.println("访问者正在运行 " + element.operationB());
    }
}
